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From: Dave Penkler <dpenkler@gmail.com>
To: gregkh@linuxfoundation.org, linux-staging@lists.linux.dev,
	linux-kernel@vger.kernel.org
Cc: dan.carpenter@linaro.org, Dave Penkler <dpenkler@gmail.com>,
	Marcello Carla' <marcello.carla@gmx.com>
Subject: [PATCH 3/4 v3] staging: gpib: Fix erroneous removal of blank before newline
Date: Thu,  5 Dec 2024 10:34:42 +0100	[thread overview]
Message-ID: <20241205093442.5796-1-dpenkler@gmail.com> (raw)

The USB_GPIB_SET_LINES command string used to be: "\nIBDC \n" but when
we were merging this code into the upstream kernel we deleted the space
character before the newline to make checkpatch happy.  That turned
out to be a mistake.

The "\nIBDC" part of the string is a command that we pass to the
firmware and the next character is a variable u8 value.
It gets set in set_control_line().

 msg[leng - 2] = value ? (retval & ~line) : retval | line;

where leng is the length of the command string.

Imagine the parameter was supposed to be "8".
With the pre-merge code the command string would be "\nIBDC8\n"
With the post-merge code the command string became "\nIBD8\n"

The firmware doesn't recognize "IBD8" as a valid command and rejects it.

Putting a "." where the parameter is supposed to go fixes the driver
and makes checkpatch happy.  Same thing with the other define and
the in-line assignment.

Reported-by: Marcello Carla' <marcello.carla@gmx.com>
Fixes: fce79512a96a ("staging: gpib: Add LPVO DIY USB GPIB driver")
Co-developed-by: Marcello Carla' <marcello.carla@gmx.com>
Signed-off-by: Marcello Carla' <marcello.carla@gmx.com>
Signed-off-by: Dave Penkler <dpenkler@gmail.com>
---
v1 -> v2
  Add more details to the commit message
  Add Signed-off by co developer
  Add spaces around assignment
  Fix tabs
v2 -> v3
Adopt and adapt the more explanatory commit message kindly
provided by Dan Carpenter

drivers/staging/gpib/lpvo_usb_gpib/lpvo_usb_gpib.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/staging/gpib/lpvo_usb_gpib/lpvo_usb_gpib.c b/drivers/staging/gpib/lpvo_usb_gpib/lpvo_usb_gpib.c
index 1a8eb3bfb61c..81c110f29e76 100644
--- a/drivers/staging/gpib/lpvo_usb_gpib/lpvo_usb_gpib.c
+++ b/drivers/staging/gpib/lpvo_usb_gpib/lpvo_usb_gpib.c
@@ -97,8 +97,8 @@ module_param(debug, int, 0644);
 #define USB_GPIB_DEBUG_ON    "\nIBDE\xAA\n"
 #define USB_GPIB_SET_LISTEN  "\nIBDT0\n"
 #define USB_GPIB_SET_TALK    "\nIBDT1\n"
-#define USB_GPIB_SET_LINES   "\nIBDC\n"
-#define USB_GPIB_SET_DATA    "\nIBDM\n"
+#define USB_GPIB_SET_LINES   "\nIBDC.\n"
+#define USB_GPIB_SET_DATA    "\nIBDM.\n"
 #define USB_GPIB_READ_LINES  "\nIBD?C\n"
 #define USB_GPIB_READ_DATA   "\nIBD?M\n"
 #define USB_GPIB_READ_BUS    "\nIBD??\n"
@@ -587,7 +587,7 @@ static int usb_gpib_command(gpib_board_t *board,
 			    size_t *bytes_written)
 {
 	int i, retval;
-	char command[6] = "IBc\n";
+	char command[6] = "IBc.\n";
 
 	DIA_LOG(1, "enter %p\n", board);
 
-- 
2.47.1


             reply	other threads:[~2024-12-05  9:34 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-12-05  9:34 Dave Penkler [this message]
2024-12-05 10:06 ` [PATCH 3/4 v3] staging: gpib: Fix erroneous removal of blank before newline Dan Carpenter

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